Many systems for treating water and wastewater include some form of aeration. Aeration is the process of adding oxygen to water or wastewater. Some aeration systems add oxygen through one or more diffusers mounted at the bottom of a tank. The tank is filled with water or wastewater to be treated, submerging the diffusers. Each diffuser includes an air conduit with small holes. When compressed air is fed into the diffusers, the air exits the diffuser through the small holes into the water or wastewater. The air forms bubbles that transfer dissolved oxygen into the water.
Oxygen transfer efficiency in an aeration process is a function of the combined surface area of air bubbles that enter the water or wastewater. The rate of oxygen transfer increases as the combined surface area of the bubbles increases. A cluster of bubbles having small diameters will have a combined surface area significantly larger than a similarly sized cluster of bubbles having larger diameters. As a result, greater oxygen transfer efficiency can be achieved with diffusers that reduce the size of air bubbles.